Abstract: Functional description in patent claims often has the problems of ambiguous meaning and overly large technical scope determined by literal meaning. The functional records have also become a difficult issue in national patent licensing, enforcement procedures and infringement proceedings. Since the revise of Japan patent law in 1994, which includes the machinery and other traditional fields emphasized on structural records, there are a large number claims of functional records and they are actually authorized. This paper studies the recording requirements and methods of interpretation of the Japanese functional limitations, so as to provide China reference to improve the relevant rules.

Key words: Japan, patent claim, functional description, explaining method